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CtRiverGreenway-parking lot improvements-NOI attachment-2012.pdf September, 2012 Notice of Intent NORWOTTUCK RAIL TRAIL Damon Road Parking Lot Improvements Northampton, Massachusetts Prepared By: Massachusetts Department of Transportation District #2 Office 811 North King Street Northampton, Massachusetts 01060 (413) 582-0599 Project File # 605065 EWO # P605065P11 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS INDEX SHEET PROJECT FILE #605065 EWO#P605065P11 # of Sheets 1. WPA Form 3 Notice of Intent (eDEP) 8 2. NOI Wetland Fee Transmittal Form 2 3. Exhibit 1 -USGS Topographic Map 1 4. Exhibit 2 -NHESP Map 1 5. Exhibit 3 -FIRM Map 1 6. Exhibit 4 -Notice of Intent Narrative 4 7. Exhibit 5 -Impact Area and Project Photos 2 8. Exhibit 6 -Checklist for Stormwater Report 8 9. Exhibit 7 -Stormwater Report 8 10. Exhibit 8 – Pre/Post Development Drainage Maps 2 11. Exhibit 9 -Professional Engineer Statement 1 12. Exhibit 10 -Notice of Intent Plans (Separate) 1 13. Exhibit 11 -Copy of Town & DEP NOI Fee Checks 1 Page 1 of 4 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS NOTICE OF INTENT NARRATIVE PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 4 INTRODUCTION Massachusetts Department of Transportation (MassDOT) in conjunction with the Department of Conservation and Recreation (DCR) is proposing a rehabilitation of the Norwottuck Bike Path from Damon Road in Northampton, Ma to Station Road in Amherst, Ma (8.5 miles). The purpose of the rehabilitation will be to improve the bike path by removing the existing pavement, tree roots that are affecting the paved surface, and bridge deck repair within the project limits. The improvements will also include additional amenities and safety features such as widening of the path in areas where topography allows and turn-around or pull-off areas along the path. As part of the rehabilitation project, the Parking Facility located on Damon Road has been redesigned to create a more accessible design for the public and increase the total number of painted parking spaces within the lot. Portions of the work will occur within the 100 ft and 200 ft Riverfront Areas, and 100 ft BVW Buffer Zone, as indicated on the design plan (see attached). This work has been described below. The Wetland Resource areas shall be protected during the construction activities using erosion and sedimentation control measures in accordance with the Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas and Massachusetts Department of Environmental Protection (DEP). EXISTING SITE DESCRIPTION The Norwottuck Rail Trail is an existing multi-use path that was constructed in 1993 and built over the abandoned railroad layout spanning from Northampton, Ma to Amherst, Ma. The trail is currently owned and maintained by the Massachusetts Department of Conservation and Recreation (DCR). The existing width of the trail varies slightly throughout with the majority of it being approximately 8’-3” wide. The path also includes four (4) tunnels running under town and state roadways as well as six (6) bridges which cross over roadways and existing rivers and brooks. The existing path paved surface has deterioration and damage which are a serious hazard to public safety. There is also recycled glass in the asphalt which has begun to separate from the asphalt binder and become loose creating a hazard for bicyclists’ tires. Side slopes and shoulders are also in need of repair as there are areas which have been washed out and have lost stabilizing vegetation. Page 2 of 4 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS NOTICE OF INTENT NARRATIVE PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 4 The latest mapping of the Estimated Habitat of Rare Wildlife and Priority Habitats of Rare Species produced by the National Heritage & Endangered Species Program (NHESP) indicates a portion of the parking facility in Northampton in Proximity to the Connecticut River to be within an area of Rare Wildlife Habitat. Throughout permitting and design, MassDOT will coordinate with the NHESP to ensure that there will be no impacts to the endangered species habitat. The existing parking facility located at Damon Road has been observed to be significantly undersized during the peak times of the year where many public users have been parking cars on the grassed areas along the edges of pavement for overflow. The parking lot serves as a main connector to the Norwottuck Rail Trail for the City of Northampton. The University of Massachusetts Rowing Team has their boathouse and access to the River at this location as well. The existing drainage mainly consists of a few shallow sump catch basins which are directed into the Connecticut River through the use of underground drainage. Portions of the parking area in front of the boathouse have eroded due to loss of vegetation and lack of proper storm water management. RESOURCE AREAS Resource areas in close proximity to the Parking Lot were delineated in August and September of 2012 and have been reviewed several times over the past 2 years during the Design process of the Rail Trail. The MAHWL and Bank along the Connecticut River are outside of the scope of the Plan but the 100 ft and 200 ft Riverfront Area boundaries are shown. Bordering Vegetated Wetlands exist between the River and the Parking lot, were delineated adjacent to the project, and are demarcated with Pink Flagging. During the Trail Design process and very recently, an eroded clay slope and stormwater outfall adjacent to the Trail Bridge and the Connecticut River, has expanded and has become unstable. The MAHWL and Bank delineation through this area have changed due to significant changes in the terrain and expansion of the outfall swale. The MAHWL from this outfall swale extends the Riverfront Area much further toward the Parking lot than the Connecticut River alone, and a small portion of the Lot is within the 100 ft Riverfront Area. The 100 ft BVW Buffer Zone extends up into the existing parking lot and is shown on the plan. Page 3 of 4 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS NOTICE OF INTENT NARRATIVE PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 4 DESCRIPTION OF WORK MassDOT proposes to rehabilitate the Norwottuck Rail Trail from Northampton, Ma to Amherst, Ma. The work will improve public safety, enhance the topography, and improve the overall usage of the bike path. The general work shall include the following: Northampton o Replacement of the existing paved surface with 3 1/2-inches of Asphalt. o Reconstruction of the Damon Road parking facility. Norwottuck Rail Trail overall o Replacement/Repair of the existing bridge decks on four (4) bridges (Cattle Crossing, Fort River, Southeast Street, and Hop Brook) o Re-alignment of the Path at the Swift Connector in Amherst, Ma to improve sight distance for users entering the rail trail. o Extension of an Access Ramp at South Pleasant Street to reduce the slope to meet the Americans with Disabilities Act (ADA) standards. o Widening of the path from 8’-3” to 10’-0” in designated areas where widening can be accomplished without environmental impacts. o Installation of turn-around areas and Pull-off areas to users. o Improvements to tunnel lighting at the underpass locations. o Other miscellaneous work. The proposed rehabilitation of the Damon Road Parking Lot shall include the total excavation of the existing parking area to the limits shown on the design plan. To improve existing conditions within the Riverfront Area, the Lot has been slightly curved away from the Connecticut River, stormwater will be managed through proper grading and a deep sump catch basin, and 3 planting areas (1area will be between the River and the Lot) will provide native plant species. The new lot has been designed to provide better access off Damon Road as well as increase the amount of parking spaces to meet demand. Stormwater is currently collected in catch basins and is directed toward the River using underground drainage structures, and the new parking lot will still direct water to the River. The new parking lot is designed to remove eroded and partially paved areas, and will add a deep sump catch basin, and both of these improvements will work in conjunction to reduce sediment in stormwater directed to the River. Page 4 of 4 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS NOTICE OF INTENT NARRATIVE PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 4 RESOURCE AREA IMPACTS BORDERING VEGETATED WETLANDS (BVW) All work pertaining to the Damon Road parking lot in the vicinity of the Bordering Vegetated Wetlands shall be limited to the 100 ft buffer zone. No work is proposed to directly or indirectly impact the wetland areas. The use of compost filter tubes along the limits of the construction shall be installed in order to protect the wetlands. The 100’ buffer zone has been shown on the design plan (see attached). RIVERFRONT AREA As indicated above, the site is located within Riverfront Areas associated with the Connecticut River. Both 100 ft and 200 ft Riverfront areas have been shown on the plans. Work within Riverfront will include areas already developed with the bike path and parking facility, and there will be a small area disturbed for the connection of the new 12” RCP. There will be a small reduction to impervious area within the Riverfront (12,461 SF existing vs. 12,330 SF proposed). Care shall be taken during construction to prevent impacts to the adjacent vegetated Riverfront at these locations. Improving existing conditions of the Riverfront Area will be achieved through multiple improvements including reducing impervious area within Riverfront, adding native plantings, reducing erosion and improving stormwater management. Page 1 of 2 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS IMPACT AREA AND PROJECT PHOTOS PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 5 EXISTING PARKING AREA Page 2 of 2 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS IMPACT AREA AND PROJECT PHOTOS PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 5 DOWNSTREAM DRAINAGE AREA swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 1 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report A. Introduction Important: When filling out forms on the computer, use only the tab key to move your cursor -do not use the return key. A Stormwater Report must be submitted with the Notice of Intent permit application to document compliance with the Stormwater Management Standards. The following checklist is NOT a substitute for the Stormwater Report (which should provide more substantive and detailed information) but is offered here as a tool to help the applicant organize their Stormwater Management documentation for their Report and for the reviewer to assess this information in a consistent format. As noted in the Checklist, the Stormwater Report must contain the engineering computations and supporting information set forth in Volume 3 of the Massachusetts Stormwater Handbook. The Stormwater Report must be prepared and certified by a Registered Professional Engineer (RPE) licensed in the Commonwealth. The Stormwater Report must include: The Stormwater Checklist completed and stamped by a Registered Professional Engineer (see page 2) that certifies that the Stormwater Report contains all required submittals.1 This Checklist is to be used as the cover for the completed Stormwater Report. Applicant/Project Name Project Address Name of Firm and Registered Professional Engineer that prepared the Report Long-Term Pollution Prevention Plan required by Standards 4-6 Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan required by Standard 82 Operation and Maintenance Plan required by Standard 9 In addition to all plans and supporting information, the Stormwater Report must include a brief narrative describing stormwater management practices, including environmentally sensitive site design and LID techniques, along with a diagram depicting runoff through the proposed BMP treatment train. Plans are required to show existing and proposed conditions, identify all wetland resource areas, NRCS soil types, critical areas, Land Uses with Higher Potential Pollutant Loads (LUHPPL), and any areas on the site where infiltration rate is greater than 2.4 inches per hour. The Plans shall identify the drainage areas for both existing and proposed conditions at a scale that enables verification of supporting calculations. As noted in the Checklist, the Stormwater Management Report shall document compliance with each of the Stormwater Management Standards as provided in the Massachusetts Stormwater Handbook. The soils evaluation and calculations shall be done using the methodologies set forth in Volume 3 of the Massachusetts Stormwater Handbook. To ensure that the Stormwater Report is complete, applicants are required to fill in the Stormwater Report Checklist by checking the box to indicate that the specified information has been included in the Stormwater Report. If any of the information specified in the checklist has not been submitted, the applicant must provide an explanation. The completed Stormwater Report Checklist and Certification must be submitted with the Stormwater Report. 1 The Stormwater Report may also include the Illicit Discharge Compliance Statement required by Standard 10. If not included in the Stormwater Report, the Illicit Discharge Compliance Statement must be submitted prior to the discharge of stormwater runoff to the post-construction best management practices. 2 For some complex projects, it may not be possible to include the Construction Period Erosion and Sedimentation Control Plan in the Stormwater Report. In that event, the issuing authority has the discretion to issue an Order of Conditions that approves the project and includes a condition requiring the proponent to submit the Construction Period Erosion and Sedimentation Control Plan before commencing any land disturbance activity on the site. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 2 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report B. Stormwater Checklist and Certification The following checklist is intended to serve as a guide for applicants as to the elements that ordinarily need to be addressed in a complete Stormwater Report. The checklist is also intended to provide conservation commissions and other reviewing authorities with a summary of the components necessary for a comprehensive Stormwater Report that addresses the ten Stormwater Standards. Note: Because stormwater requirements vary from project to project, it is possible that a complete Stormwater Report may not include information on some of the subjects specified in the Checklist. If it is determined that a specific item does not apply to the project under review, please note that the item is not applicable (N.A.) and provide the reasons for that determination. A complete checklist must include the Certification set forth below signed by the Registered Professional Engineer who prepared the Stormwater Report. Registered Professional Engineer’s Certification I have reviewed the Stormwater Report, including the soil evaluation, computations, Long-term Pollution Prevention Plan, the Construction Period Erosion and Sedimentation Control Plan (if included), the Longterm Post-Construction Operation and Maintenance Plan, the Illicit Discharge Compliance Statement (if included) and the plans showing the stormwater management system, and have determined that they have been prepared in accordance with the requirements of the Stormwater Management Standards as further elaborated by the Massachusetts Stormwater Handbook. I have also determined that the information presented in the Stormwater Checklist is accurate and that the information presented in the Stormwater Report accurately reflects conditions at the site as of the date of this permit application. Registered Professional Engineer Block and Signature Signature and Date Checklist Project Type: Is the application for new development, redevelopment, or a mix of new and redevelopment? New development Redevelopment Mix of New Development and Redevelopment swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 3 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) LID Measures: Stormwater Standards require LID measures to be considered. Document what environmentally sensitive design and LID Techniques were considered during the planning and design of the project: No disturbance to any Wetland Resource Areas Site Design Practices (e.g. clustered development, reduced frontage setbacks) Reduced Impervious Area (Redevelopment Only) Minimizing disturbance to existing trees and shrubs LID Site Design Credit Requested: Credit 1 Credit 2 Credit 3 Use of “country drainage” versus curb and gutter conveyance and pipe Bioretention Cells (includes Rain Gardens) Constructed Stormwater Wetlands (includes Gravel Wetlands designs) Treebox Filter Water Quality Swale Grass Channel Green Roof Other (describe): Standard 1: No New Untreated Discharges No new untreated discharges Outlets have been designed so there is no erosion or scour to wetlands and waters of the Commonwealth Supporting calculations specified in Volume 3 of the Massachusetts Stormwater Handbook included. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 4 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 2: Peak Rate Attenuation Standard 2 waiver requested because the project is located in land subject to coastal storm flowage and stormwater discharge is to a wetland subject to coastal flooding. Evaluation provided to determine whether off-site flooding increases during the 100-year 24-hour storm. Calculations provided to show that post-development peak discharge rates do not exceed predevelopment rates for the 2-year and 10-year 24-hour storms. If evaluation shows that off-site flooding increases during the 100-year 24-hour storm, calculations are also provided to show that post-development peak discharge rates do not exceed pre-development rates for the 100-year 24-hour storm. Standard 3: Recharge Soil Analysis provided. Required Recharge Volume calculation provided. Required Recharge volume reduced through use of the LID site Design Credits. Sizing the infiltration, BMPs is based on the following method: Check the method used. Static Simple Dynamic Dynamic Field1 Runoff from all impervious areas at the site discharging to the infiltration BMP. Runoff from all impervious areas at the site is not discharging to the infiltration BMP and calculations are provided showing that the drainage area contributing runoff to the infiltration BMPs is sufficient to generate the required recharge volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume. Recharge BMPs have been sized to infiltrate the Required Recharge Volume only to the maximum extent practicable for the following reason: Site is comprised solely of C and D soils and/or bedrock at the land surface M.G.L. c. 21E sites pursuant to 310 CMR 40.0000 Solid Waste Landfill pursuant to 310 CMR 19.000 Project is otherwise subject to Stormwater Management Standards only to the maximum extent practicable. Calculations showing that the infiltration BMPs will drain in 72 hours are provided. Property includes a M.G.L. c. 21E site or a solid waste landfill and a mounding analysis is included. 1 80% TSS removal is required prior to discharge to infiltration BMP if Dynamic Field method is used. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 5 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 3: Recharge (continued) The infiltration BMP is used to attenuate peak flows during storms greater than or equal to the 10-year 24-hour storm and separation to seasonal high groundwater is less than 4 feet and a mounding analysis is provided. Documentation is provided showing that infiltration BMPs do not adversely impact nearby wetland resource areas. Standard 4: Water Quality The Long-Term Pollution Prevention Plan typically includes the following: Good housekeeping practices; Provisions for storing materials and waste products inside or under cover; Vehicle washing controls; Requirements for routine inspections and maintenance of stormwater BMPs; Spill prevention and response plans; Provisions for maintenance of lawns, gardens, and other landscaped areas; Requirements for storage and use of fertilizers, herbicides, and pesticides; Pet waste management provisions; Provisions for operation and management of septic systems; Provisions for solid waste management; Snow disposal and plowing plans relative to Wetland Resource Areas; Winter Road Salt and/or Sand Use and Storage restrictions; Street sweeping schedules; Provisions for prevention of illicit discharges to the stormwater management system; Documentation that Stormwater BMPs are designed to provide for shutdown and containment in the event of a spill or discharges to or near critical areas or from LUHPPL; Training for staff or personnel involved with implementing Long-Term Pollution Prevention Plan; List of Emergency contacts for implementing Long-Term Pollution Prevention Plan. A Long-Term Pollution Prevention Plan is attached to Stormwater Report and is included as an attachment to the Wetlands Notice of Intent. Treatment BMPs subject to the 44% TSS removal pretreatment requirement and the one inch rule for calculating the water quality volume are included, and discharge: is within the Zone II or Interim Wellhead Protection Area is near or to other critical areas is within soils with a rapid infiltration rate (greater than 2.4 inches per hour) involves runoff from land uses with higher potential pollutant loads. The Required Water Quality Volume is reduced through use of the LID site Design Credits. Calculations documenting that the treatment train meets the 80% TSS removal requirement and, if applicable, the 44% TSS removal pretreatment requirement, are provided. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 6 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 4: Water Quality (continued) The BMP is sized (and calculations provided) based on: The ½” or 1” Water Quality Volume or The equivalent flow rate associated with the Water Quality Volume and documentation is provided showing that the BMP treats the required water quality volume. The applicant proposes to use proprietary BMPs, and documentation supporting use of proprietary BMP and proposed TSS removal rate is provided. This documentation may be in the form of the propriety BMP checklist found in Volume 2, Chapter 4 of the Massachusetts Stormwater Handbook and submitting copies of the TARP Report, STEP Report, and/or other third party studies verifying performance of the proprietary BMPs. A TMDL exists that indicates a need to reduce pollutants other than TSS and documentation showing that the BMPs selected are consistent with the TMDL is provided. Standard 5: Land Uses With Higher Potential Pollutant Loads (LUHPPLs) The NPDES Multi-Sector General Permit covers the land use and the Stormwater Pollution Prevention Plan (SWPPP) has been included with the Stormwater Report. The NPDES Multi-Sector General Permit covers the land use and the SWPPP will be submitted prior to the discharge of stormwater to the post-construction stormwater BMPs. The NPDES Multi-Sector General Permit does not cover the land use. LUHPPLs are located at the site and industry specific source control and pollution prevention measures have been proposed to reduce or eliminate the exposure of LUHPPLs to rain, snow, snow melt and runoff, and been included in the long term Pollution Prevention Plan. All exposure has been eliminated. All exposure has not been eliminated and all BMPs selected are on MassDEP LUHPPL list. The LUHPPL has the potential to generate runoff with moderate to higher concentrations of oil oil and grease (e.g. all parking lots with >1000 vehicle trips per day) and the treatment train includes an oil grit separator, a filtering bioretention area, a sand filter or equivalent. Standard 6: Critical Areas The discharge is near or to a critical area and the treatment train includes only BMPs that MassDEP has approved for stormwater discharges to or near that particular class of critical area. Critical areas and BMPs are identified in the Stormwater Report. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 7 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 7: Redevelopments and Other Projects Subject to the Standards only to the maximum extent practicable The project is subject to the Stormwater Management Standards only to the maximum Extent Practicable as a: Limited Project Small Residential Projects: 5-9 single family houses or 5-9 units in a multi-family development provided there is no discharge that may potentially affect a critical area. Small Residential Projects: 2-4 single family houses or 2-4 units in a multi-family development with a discharge to a critical area Marina and/or boatyard provided the hull painting, service and maintenance areas are protected from exposure to rain, snow, snow melt and runoff Bike Path and/or Foot Path Redevelopment Project Redevelopment portion of mix of new and redevelopment. Certain standards are not fully met (Standard No. 1, 8, 9, and 10 must always be fully met) and an explanation of why these standards are not met is contained in the Stormwater Report. The project involves redevelopment and a description of all measures that have been taken to improve existing conditions is provided in the Stormwater Report. The redevelopment checklist found in Volume 2 Chapter 3 of the Massachusetts Stormwater Handbook may be used to document that the proposed stormwater management system (a) complies with Standards 2, 3 and the pretreatment and structural BMP requirements of Standards 4-6 to the maximum extent practicable and (b) improves existing conditions. Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan must include the following information: Narrative; Construction Period Operation and Maintenance Plan; Names of Persons or Entity Responsible for Plan Compliance; Construction Period Pollution Prevention Measures; Erosion and Sedimentation Control Plan Drawings; Detail drawings and specifications for erosion control BMPs, including sizing calculations; Vegetation Planning; Site Development Plan; Construction Sequencing Plan; Sequencing of Erosion and Sedimentation Controls; Operation and Maintenance of Erosion and Sedimentation Controls; Inspection Schedule; Maintenance Schedule; Inspection and Maintenance Log Form. A Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan containing the information set forth above has been included in the Stormwater Report. swcheck (Damon Rd).doc • 04/01/08 Stormwater Report Checklist • Page 8 of 8 Massachusetts Department of Environmental Protection Bureau of Resource Protection -Wetlands Program Checklist for Stormwater Report Checklist (continued) Standard 8: Construction Period Pollution Prevention and Erosion and Sedimentation Control (continued) The project is highly complex and information is included in the Stormwater Report that explains why it is not possible to submit the Construction Period Pollution Prevention and Erosion and Sedimentation Control Plan with the application. A Construction Period Pollution Prevention and Erosion and Sedimentation Control has not been included in the Stormwater Report but will be submitted before land disturbance begins. The project is not covered by a NPDES Construction General Permit. The project is covered by a NPDES Construction General Permit and a copy of the SWPPP is in the Stormwater Report. The project is covered by a NPDES Construction General Permit but no SWPPP been submitted. The SWPPP will be submitted BEFORE land disturbance begins. Standard 9: Operation and Maintenance Plan The Post Construction Operation and Maintenance Plan is included in the Stormwater Report and includes the following information: Name of the stormwater management system owners; Party responsible for operation and maintenance; Schedule for implementation of routine and non-routine maintenance tasks; Plan showing the location of all stormwater BMPs maintenance access areas; Description and delineation of public safety features; Estimated operation and maintenance budget; and Operation and Maintenance Log Form. The responsible party is not the owner of the parcel where the BMP is located and the Stormwater Report includes the following submissions: A copy of the legal instrument (deed, homeowner’s association, utility trust or other legal entity) that establishes the terms of and legal responsibility for the operation and maintenance of the project site stormwater BMPs; A plan and easement deed that allows site access for the legal entity to operate and maintain BMP functions. Standard 10: Prohibition of Illicit Discharges The Long-Term Pollution Prevention Plan includes measures to prevent illicit discharges; An Illicit Discharge Compliance Statement is attached; NO Illicit Discharge Compliance Statement is attached but will be submitted prior to the discharge of any stormwater to post-construction BMPs. Page 1 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 STORMWATER ANALYSIS INTRODUCTION As part of the Norwottuck Rail Trail rehabilitation project in the Towns of Amherst, Hadley and Northampton, the reconstruction of the Damon Road parking lot located in Northampton will be included. This reconstruction will include a redesign of the existing lot as well as improvements to the stormwater system and the addition of parking spaces. The parking lot has also been designed improve upon existing conditions with Riverfront Areas, and to accommodate the existing UMass Rowing Team’s boathouse facility. EXISTING CONDITIONS The existing parking facility contains one (1) catch basin located at the northern corner of the parking lot. This catch basin is routed into a drain manhole which connects with a drain line from Damon Road and directs to water into a downstream swale outleting into the Connecticut River. During a site visit there was ponding and drainage issues noted where stormwater was not being directed into the catch basins. The majority of the paved parking area located on the southern portion of the lot currently flows toward the Damon Road street drainage or is collected into two (2) catch basins which then connects into the Damon Road underground drainage. Overall the majority of the site drainage eventually outlets into the Connecticut River located approximately 200’ from the parking lot facility. EXISTING HYDROLOGY In order to analyze the existing hydrology, the lot was broken up into six (6) subcatchments of which four (4) critical design points have been chosen to be studied. These design points include the overland flow going to Damon Road, two (2) existing catch basins on the southern portion, overland flow to the northern portion of the site, and the drain manhole located on the northern portion of the site. The Rational Formula has been used to determine the runoffs for the various storm events. Table 1 illustrates the results. (See existing drainage map) Page 2 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 TABLE 1: EXISTING DRAINAGE CALCULATIONS RATIONAL FORMULA 10-YEAR 25-YEAR 50-YEAR 100-YEAR AREA (SF) C i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) PRE AREA 1 PAVED AREA 11,157 0.9 6.0 1.38 7.0 1.61 7.6 1.75 8.5 1.96 GRASS 7,220 0.4 6.0 0.40 7.0 0.46 7.6 0.50 8.5 0.56 1.78 2.07 2.25 2.52 PRE AREA 2 PAVED AREA 1,234 0.9 6.0 0.15 7.0 0.18 7.6 0.19 8.5 0.22 GRASS 376 0.4 6.0 0.02 7.0 0.02 7.6 0.03 8.5 0.03 0.17 0.20 0.22 0.25 PRE AREA 3 GRASS 10,990 0.4 6.0 0.61 7.0 0.71 7.6 0.77 8.5 0.86 PRE AREA 4 PAVED AREA 10,584 0.9 6.0 1.31 7.0 1.53 7.6 1.66 8.5 1.86 PRE AREA 5 PAVED AREA 1,238 0.9 6.0 0.15 7.0 0.18 7.6 0.19 8.5 0.22 GRASS 5,013 0.4 6.0 0.31 7.0 0.36 7.6 0.39 8.5 0.44 0.46 0.54 0.58 0.66 PRE AREA 6 PAVED AREA 2,548 0.9 6.0 0.32 7.0 0.37 7.6 0.40 8.5 0.45 GRASS 3,259 0.4 6.0 0.19 7.0 0.23 7.6 0.24 8.5 0.27 0.51 0.60 0.64 0.72 PROPOSED HYDROLOGY The proposed parking lot design will include the use of the existing catch basin along with the installation of an additional catch basin to collect stormwater at the new low point and direct it to the Connecticut River. The remainder of the parking lot facility will function just as it had in the existing conditions. Table 2 illustrates the results of this analysis. (See proposed drainage map) Page 3 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 TABLE 2: Proposed Drainage Calculations RATIONAL FORMULA 10-YEAR 25-YEAR 50-YEAR 100-YEAR AREA (SF) C i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) i (IN/HR) Q (CFS) POST AREA 1A PAVED AREA 1,476 0.9 6.0 0.18 7.0 0.21 7.6 0.23 8.5 0.26 POST AREA 1B PAVED AREA 2,364 0.9 6.0 0.29 7.0 0.34 7.6 0.37 8.5 0.42 GRASS 7,777 0.4 6.0 0.43 7.0 0.50 7.6 0.54 8.5 0.61 0.90 1.05 1.14 1.29 POST AREA 2 PAVED AREA 1,616 0.9 6.0 0.20 7.0 0.23 7.6 0.25 8.5 0.28 GRASS 224 0.4 6.0 0.01 7.0 0.01 7.6 0.02 8.5 0.02 0.21 0.24 0.27 0.30 PRE AREA 3 GRASS 7,214 0.4 6.0 0.40 7.0 0.46 7.6 0.50 8.5 0.56 POST AREA 4A PAVED AREA 10,111 0.9 6.0 1.25 7.0 1.46 7.6 1.59 8.5 1.78 POST AREA 4B PAVED AREA 10,718 0.9 6.0 1.33 7.0 1.55 7.6 1.68 8.5 1.88 2.58 3.01 3.27 3.66 POST AREA 5 PAVED AREA 1,784 0.9 6.0 0.25 7.0 0.30 7.6 0.32 8.5 0.36 GRASS 4,467 0.4 6.0 0.27 7.0 0.32 7.6 0.34 8.5 0.39 0.52 0.52 0.62 0.66 0.75 POST AREA 6 PAVED AREA 3,885 0.9 6.0 0.38 7.0 0.45 7.6 0.49 8.5 0.54 GRASS 1,880 0.4 6.0 0.16 7.0 0.19 7.6 0.21 8.5 0.23 0.55 0.64 0.70 0.77 Page 4 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 RESULTS The proposed design will result in a 17-percent increase in impervious area (4,658 SF) overall. Since the design is redevelopment there will only be improvements to the maximum extent practicable. Therefore, currently there will be no proposed groundwater recharge BMP’s except the existing and proposed grassed areas. Since this facility is in close proximity to the Connecticut River and the majority of the overland and groundwater currently flows in that direction, this will not have any significant impact to the groundwater conditions. The results of the analysis indicate a reduction in offsite stormwater flows for design points 1 and 3 which will reduce the overland flows into the Damon Road drainage system and to the northern portion of the site. There will however be a slight increase into the catch basins shown as design point 2. This increase as indicated on Table 3 below is very minimal and will have little to no impacts on the drainage system. There will be an increase to design point 4 due to the change in parking layout and the installation of a new catch basin which will connect into an existing drain manhole on the northern portion of the site. Preliminary calculations have been conducted to show that the downstream underground drainage piping will be able to handle this additional flow during all storm events. There will be no offsite impacts due to this increase as these flows are directed into the Connecticut River. See Table 3 below for a summary. TABLE 3: Analysis Results (Flows in cfs) 10-YEAR 25-YEAR 50-YEAR 100-YEAR Existing Proposed Existing Proposed Existing Proposed Existing Proposed DESIGN POINT 1 1.78 0.90 2.07 1.05 2.25 1.14 2.52 1.29 DESIGN POINT 2 0.17 0.21 0.20 0.24 0.22 0.27 0.25 0.30 DESIGN POINT 3 0.61 0.40 0.71 0.46 0.77 0.50 0.86 0.56 DESIGN POINT 4 1.31 2.58 1.53 3.01 1.66 3.27 1.86 3.66 AREA 5 0.46 0.52 0.54 0.62 0.58 0.66 0.66 0.66 0.75 AREA 6 0.51 0.54 0.60 0.64 0.64 0.70 0.72 0.77 TOTALS 4.84 5.15 5.65 6.02 6.12 6.54 6.87 7.33 Page 5 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 STORMWATER COMPLIANCE REPORT The proposed redevelopment shall meet the stormwater management standards to the maximum extent practicable. The following analysis shall indicate how the proposed design shall employ best management practices for each standard. STANDARD 1: NO NEW UNTREATED DISCHARGES The MA Stormwater Handbook requires that no new stormwater conveyances may discharge untreated stormwater directly to or cause erosion in wetlands or waters of the Commonwealth that may adversely impact the downstream waterways. All paved parking areas shall be swept clean of dust and debris during the annual maintenance schedule. The stormwater from the impervious surfaces shall be directed into catch basins. The two (2) major catch basins as shown on the proposed hydrology map (Appendix A) collecting areas 4a and 4b shall be equipped with deep sumps to collect suspended solids. The existing outfall for this area is currently under design to be reconstructed with new stone rip rap for erosion control and new underground piping with a concrete flared end. Therefore, the reconstruction of the existing outfall shall not be included under this project. The current outfall was inspected in the field and due to the current condition it does not appear that any additional stormwater would create additional erosion. STANDARD 2: PEAK RATE ATTENUATION Standard 2 states that the proposed stormwater management system shall be designed so that post development peak discharge rates do not exceed pre development peak discharge rates except in areas where subject to coastal storm flowage. As discussed in the Drainage Analysis Report, there will be some minor increases at two (2) design points due to the slight increase in paved area. Since these design points ultimately discharge into the Connecticut River, it has been determined that there will be no impacts on the downstream drainage from this small increase in offsite flows. This standard has been met to the maximum extent practicable within the limitations of property, proximity to the wetlands and riverfront, and costs. Page 6 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 STANDARD 3: RECHARGE TO GROUNDWATER The intent of Standard 3 is to ensure that the infiltration volume of precipitation into the ground under post-development conditions is at least as much as the infiltration volume under predevelopment conditions. The standard states that the amount of groundwater recharge shall be based upon existing soil condition recharge rates. The total proposed impervious area for the parking lot reconstruction is 31,419 S.F. This is a 17-percent increase (4,658 S.F.) in impervious surface area from the existing 26,761 S.F. Soil data from the USDA National Resourced Conservation Service (NRCS) indicate that the site is primarily consisting of Winooski Silt Loam which is stated as being a Hydraulic Soil Group (HSG) B. According to Standard 3 the required recharge volume should be calculated by the Total Impervious Area times 0.35 inches of of runoff. The following calculation has been provided. Required Recharge Volume = (Total Impervious Area) x (0.35 in) /12 Required Recharge Volume = (31,419 S.F.) x (0.35 in/12) = 916 C.F. Considering that the majority of the site flows into the Connecticut River and the close proximity of the parking facility to the wetlands and riverfront areas it does not appear necessary or practical to provide additional groundwater recharge for the parking facility. Some alternatives for this requirement were considered which includes the use of pervious pavement and the installation of a Rain Garden. It was determined that the use of pervious pavement in this area would not be practicable as there may be a chance of high groundwater and poor infiltrating soils with a Silt Loam as well a continuous maintenance issue that would be the result of installing these types of BMP’s. STANDARD 4: WATER QUALITY Standard 4 requires stormwater management systems be designed to remove 80% of the average annual post-construction load of Total Suspended Solids (TSS). The proposed site will produce lower than normal potential pollutant loading since there will be no winter sanding on the site and it does not receive high annual traffic volumes. Therefore, this standard will only be met to the maximum extent practicable. In order to facilitate TSS removal two (2) stormwater BMP’s will be utilized. The first will be the annual sweeping of the parking lot to remove sand and debris from the paved parking surface. The second will be the installation of deep sump catch basins. See standard 9 for the long term pollution prevention plan. Page 7 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 STANDARD 5: LAND USES WITH HIGHER POTENTIAL POLLUTANT LOADING The proposed redevelopment project is NOT considered a land use with Higher Potential Pollutant Loads and therefore Standard 5 is not applicable. STANDARD 6: STORMWATER DISCHARGES TO CRITICAL AREAS Standard 6 is not applicable because the proposed redevelopment project is not located near any critical areas as defined in the Massachusetts Stormwater Handbook. STANDARD 7: REDEVELOPMENT The proposed redevelopment project has been designed to meet the current Stormwater Management Standards to the maximum extent practicable as defined in the Massachusetts Stormwater Handbook. Measures have been taken to improve the existing conditions within the confined limitations of the parking facility as described under standards 1 through 4 described above. STANDARD 8: CONSTRUCTION PERIOD POLLUTION PREVENTION AND EROSION CONTROL Construction period erosion controls have been included on the design plan for the parking facility which includes the use of compost filter tubes and stockpiling areas. All measures shall be in conformance with the Massachusetts Erosion and Sediment Control Guidelines for Urban and Suburban Areas. See design plans for details. As the proposed project will involve more than one (1) acre of earth disturbance, a NPDES Construction General Permit will be required. The Contractor will be responsible for submitting a Stormwater Pollution Prevention Plan (SWPPP) before land disturbance begins. The SWPPP will include the entire project. The SWPPP will require inspections of all erosion controls and the potential runoff of sediment throughout the duration of the project. Construction Sequence 1. Install compost filter tubes in accordance with the design plans. 2. Remove Vegetation and existing parking surface as required. 3. Begin construction of new parking facility and drainage and utilize stockpiling area for material in the locations as shown on the design plans. 4. Loam and seed all disturbed areas within the project limits. 5. Permanently stabilize all additional disturbed areas. 6. Remove erosion and sedimentation control measures Page 8 of 8 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS STORMWATER REPORT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 7 Construction Operation and Maintenance The erosion control measures shall be inspected periodically or after a storm event to ensure that they are functioning correctly. Damaged areas shall be repaired immediately prior to any construction activities resuming. The contractor shall keep a log of all inspections and issues if present. STANDARD 9: OPERATION AND MAINTENANCE PLAN The long term maintenance of the facility shall be the responsibility of the Massachusetts Department of Conservation and Recreation (DCR). The following schedule shall be followed and logs shall be kept of the inspection and maintenance: 1. Parking lot shall be swept two (2) times per year. Once in the early spring and once in the early fall prior to winter. 2. Catch basins shall be inspected two (2) times per year minimum and shall be cleaned at least once per year or as necessary. 3. Outfalls shall be inspected once per year for accumulation of debris and sediment. Outlets shall be cleaned as necessary. STANDARD 10: PROHIBITION OF ILLICIT DISCHARGES No illicit discharges are known to exist in the project area. During construction, all existing drainage structures will be inspected to verify that connections are only from stormwater pipes. A 'No lllicit Discharge Compliance Statement' shall be submitted prior to the discharge of any stormwater to post-construction BMP's. FED. AID PROJ. NO. SHEET NO. TOTAL SHEETS NORTHAMPTON -HADLEY -AMHERST NORWOTTUCK RAIL TRAIL REHABILITATION STATE MASS. PROJECT FILE NO. -EXISTING HYDROLOGY MAP 605065 605065[75%]HD4B (DAMON ROAD PLAN).DWG 1 2 FED. AID PROJ. NO. SHEET NO. TOTAL SHEETS NORTHAMPTON -HADLEY -AMHERST NORWOTTUCK RAIL TRAIL REHABILITATION STATE MASS. PROJECT FILE NO. -PROPOSED HYDROLOGY MAP 605065 605065[75%]HD4B (DAMON ROAD PLAN).DWG 2 2 Page 1 of 1 NORTHAMPTON: NORWOTTUCK RAIL TRAIL DAMON ROAD PARKING LOT IMPROVEMENTS PROFESSIONAL ENGINEER STATEMENT PROJECT FILE #605065 EWO#P605065P11 EXHIBIT 9 PROFESSIONAL ENGINEER STATEMENT As a State Agency, MassDOT must comply with all State and Federal requirements and prepare project documents in accordance with, to name a few, the 2006 Project Development and Design Guide, the American Association of State Highway and Transportation Officials Manual, the MassDOT-Highway Stormwater Handbook, DEP Stormwater Management Standards, etc. All project documents are prepared under the auspices of the MassDOT Chief Engineer. As such, MassDOT does not provide a professional engineers stamp or signature with any plans and submittals.